Answer:
c = 20r is the equation
Explanation:
From the figure given in the question,
cost of 1 dozen of rose = 10 which is 1*20
cost of 2 dozens of rose = 40 which is 2*20
cost of 3 dozens of rose = 60 which is 3*20
cost of 4 dozens of rose = 80 which is 4*20
cost of 5 dozens of rose = 100 which is 5*20
similarly, we can say
cost of r dozens of rose = r*20 = 20r